In Calendar month view, besides tapping on the ‘+’ button to add an event, you can also tap and hold on any day. (Thanks @Alan)

When receiving a call from a number not in your phonebook, the phone will display the location of the phone area code under the number… i.e. + 1 (514) 321 2345 will display Quebec, Canada in a smaller font under the number and not just in the call history. (Thanks @Kubus)

Use current location in Weather.app. (Thanks @Andy)

Flagging Support in Mails. app

In settings you can switch what option you get when you tap and hold on links in Safari: either open in background or in a new page. (Thanks @Andy)

Swipe left and right to change months in calendar on iPad (Thanks @Shaun)

Swipe to delete songs (Thanks @Derek)

Buy More Storage option for iCloud

Ability to set custom sound for alerts (New Message, New Voicemail, News Mail, Sent Mail etc.)

Define your own words in Offline Dictionary

Apps fades to homescreen when crashes, rather than flicking off.

Ability to Enable/Disable Badges on Apps

When you download an app on the iTunes on your PC, the app is automatically pushed to your iDevice and installed.

Streaming Song details such as Track and Artist info to Bluetooth audio devices. (Thanks @Roy)

When your alarm goes off you can snooze it from lockscreen or slide to turn off. (Note: This is an updated style, you slide on the notifications area, just below the clock, rather than the previous “Slide to Unlock” location. ) (Thanks @Terry)

You can add multiple twitter accounts and choose what account to send a tweet from.

Delete each app’s data

iTunes Tune Store

Real-time stock quotes

VoiceOver item chooser

Option to speak text selection

When your phone is locked and you switch to Ringing from Silent, the Ringing indicator also shows the volume level bar.

You can choose multiple Emails and mark them as read

Download more than one app simultaneously. No waiting for the previous app to be completed

You can choose if to display Weather and Stock Widges on Notification Center.

New Voice in Voice Control

You can re arrange the preference of apps in Notification Center. (Eg: You can set the Weather widget to be always on top, Messages next etc..)

Ability to set maximum messages downloaded through email to 1000 instead of 250

Sponsored links in Google Maps

Double-tap the home button while watching a YouTube video to display who uploaded the video

Scrolling titles for YouTube videos

Time mid-call invitation alerts

Set up Airport / Time Capsule on your iOS device

Invitation alerts to FaceTime while taking a call

Arabic Language Support in VoiceOver

Links can be opened in the background

Integrate Twitter user pictures to Contacts. Sync them

Native 1080p video playback in iPad 2

Japanese or Buddhist calendars support

Year View in iPad cal

Native Support for turn based games in Game Center

Search Within the contents of an email

Indentation Control in Mails.app

Individual Site Data can be deleted from Safari

iOS 5 address book has a field for Twitter, Facebook, Flickr, LinkedIn and Myspace. (iOS 5 to integrate more social networks?

Specific ‘search on page’ area integrated in the ipad keyboard (hit google when in safari) (Thanks @Michael)

Have one app updating while others say “waiting…,” then you pause the app updating. You then immediately put the iDevice on sleep. Next, when you wake up your iDevice, all of them will be paused. You can tap more than one app to have more than one downloading. (thanks @Michael)

Personal Hotspot settings are now found under ‘Network’ settings.

GIFs are animated when sent through iMessages. It’s not animated in Photos.app.